Recursive clone in get_libwallet_api.sh

[NewEraCracker]

• Combines submodule init and update into one command and does so recursively
• This should alleviate the pain of people that don't recursively clone

[NewEraCracker]

First commit also submitted upstream: https://github.com/monero-project/monero-gui/pull/1946

[NewEraCracker]

Updating the libraries is, unfortunately, a bad idea and causes severe build problems on my system. I have removed those changes from this PR.